Method of drilling with high velocity jet cutter rock bit



R. A. BOBO Dec. 3, 1963 METHOD OF DRILLING WITH HIGH VELOCITY JET CUTTERROCK BIT Filed Aug. 28, 1959 3 Sheets-Sheet l FIG FIG. 5

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METHOD OF DRILLING WITH HIGH VELOCITY JET CUTTER ROCK BIT Filed Aug. 28,1959 3 Sheets-Sheet 2 INVEN TOR.

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A T TORNEYS Dec. 3, 1963 R. A. B Bo 3,112,800

METHOD OF DRILLING WITH HIGH VELOCITY JET CUTTER ROCK BIT Filed Aug.,28,1959 :s Sheets-Sheet s I01 4 F/G. 7 f

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" ATTORNEYS United States Patent 3,112,860 METHGD OF DREHNG i /11THHlGii VELGQETY .lE'l (IUTTER BUCK Bll Roy A. lBobo, Houston, Tern,assignor to Phillips Petro= leum Company, a corporation of DelawareFiled Aug. 28, 1959, Ser. No. 836,817 8 Claims. {6L 1755-67) Thisinvention relates to high velocity jet cut-ters for use with rotary rockbits for drilling wells.

In drilling deep wells, rock formations are frequently encountered whichare extremely hard and slow to drill even with the most modern rotarydrill equipment. In using rotary drill bits it is noted that the teethon the gage and the outside periphery of the bit cone always showgreater uvear than the teeth nearer the center of the hole. The reasonfor this greater wear on the teeth near the periphery of the borehole isthat the overburden stress acts downward at the wall of the hole wlr'lethe downward stress at the center of the hole, due to the pull ofgravity of overlying strata, has been removed. This latter conditionoccurs when the borehole is free from all liquids. For this reason withan empty borehole as far as liquid is concerned and without solidoverburden to compress the rock in the bottom of the hole, the bottomdrills much easier than that portion of the hole near the wall. It isknown that when drilling with circulating gas as a means for removingcuttings the drilling rate is more rapid than when drilling in thepresence of a column of drilling mud. Under the latter condition thepressure on the bottom of the hole may be several thousand pounds persquare inch tending to compress the rock at the bottom of the hole andmore energy is required to drill away the rock under this condition.

According to this invention an annular groove is out downward around theperiphery of the well bore leaving a core of rock in the center of thehole. After cutting such a groove all lateral forces tending to compressthe central portion of the roca or core are removed and removal of thiscore is then merely a matter of crushing the core of rock. According tothis invention, there is employed a fluid jetted under extremely highpressure through a small nozzle which operates as a cutting means. Byplacing suitable nozzles on a drill head and near the outer peripherythereof, and orienting them to eject fluid in a downward direction in awell, then upon forcing fluid, either liquid or gas, under sufiicientlyhigh pressure therethrough and rotating the drill head, an annulargroove is cut. As mentioned, a gas can be used, such as air, naturalgas, or gas evolved by chemical reaction, such as oxygen evolved uponthe catalytic decomposition of hydrogen peroxide, or gases of combustionformed by the burning of, for example, such an easily combustiblematerial as a propellant composition normally used in the propulsion ofmissiles. A catalyst suitable for the rapid decomposition of hydrogenperoxide is fully described in Us. Patent 2,680,487. These catalysts arefinely divided silver, finely divided platinum, the alkali metalpermanganates, the alkaline earth metal permanganates and manganesedioxide. The combustion of a hydrocarbon fuel with free oxygen liberatedfrom hydrogen peroxide by these catalysts also provides large volumes ofgases, and when injected under high pressure through a suitable nozzledirected in a generally downward direction, these gases erode theformation at the bottom of the drill hole according to this invention.As mentioned above, upon rotation of such a nozzle around the peripheryof the borehole, an annular groove is formed surrounding a core of rock.

According to this invention when using extremely high pressure gas orliquids under high pressure, even the hard- Patented Dec. 3, 19-653 estof rock can be relatively rapidly eroded or ground away therebypermitting rapid drilling of deep wells.

An object of this invention is to provide a method and apparatus fordrilling deep wells at a more rapid rate than is presently possible.

Another object of this invention is to provide a method and apparatusfor drilling deep wells which is less costly than present apparatus andmethods.

Still other objects and advantages of this invention will be realizedupon reading the following description which, taken with the attacheddrawing, forms a part of this specilication.

In the drawing,

FEGURE 1 is a view looking at the underside of a drill bit of thisinvention.

FIGURE 2 is an elevational view, partly in section, of one embodiment ofapparatus of this invention.

FXGURE 3 is an elevational view, in section, taken on the line 3-3 ofFIGURE 2.

PEGURE 4 is an elevational view, partly in section, of anotherembodiment of this invention.

FIGURE 5 is a sectional view of another embodiment of the drill bit ofthis invention.

FEGURE 6 is an elevational view, partly in section, of anotherembodiment of this invention.

FIGURE 7 is a sectional view of another embodiment of drill bit of thisinvention.

FIGURE 8 is a bot-tom view of FIGURE 7.

FEGURE 9 is a sectional view of still another embodiment or drill bit.

FIGURE ll) is a bottom view of the apparatus of FIG- URE 9.

in the drawing, and particularly in FIGURES 2 and 3, a borehole into theearth is identified by reference nu- .eral 11. Derrick 32a supports adraw works or hoist, not shown, the latter being provided for loweringand raising the equipment into and from, respectively, the well bore.Disposed within this borehole is a drill tubing 12 at the bottom end ofwhich is threaded or otherwise suitably attached a drill bit 13. Thisdrill bit is provided with one or more rotary drill cones 14 similar tothose used in conventional rotary drill bits. These cones are supportedby shafts 35' which, in turn, are supported by support arms 35 extendingdownward from the main body of the drill bit. In this embodiment thereare two drill cones 1d placed opposite each other. At degrees from eachdrill cone is positioned nozzle bases 15. These nozzle bases or supports15 are so constructed that upon insertion of nozzle inserts 23:, fluidflows in a generally downward direction. By arranging these nozzles sothat one follows the other in rotation of the bit, cutting or" thegroove is quite rapid. it is found that upon cutting such a groove aseven the narrow groove 25 the remaining core is relatively easilycrushed and the rock fragments disin tegrated for easy removal by eithercirculating drilling mud or gas.

As illustrated in FIGURES 2 and 3, drilling mud 27 is pumped by asurface pump 28 through drive head 33 into the drill tubing 12 and upthe annulus outside drill tubing 12. It is intended that the mud pump 28exert a more or less conventional mud circulating pressure. However,under some conditions it is desired that pump 28 exert a pressureseveral hundred pounds more than that required for the normalcirculation of the drilling mud. A pressure considerably greater thanthat stated relative to pump 28 is required for the operation of thedrill bits of this invention. As illustrated in FIGURE 2, a suitablepressure multiplying motor-pump assembly is provided down hole in thedrill tubing. This assembly includes a fluid motor 16 resting upon aflange :18 in tubing 12. One or more O-ring seals 19 are provided toprevent leakage of fluid between the motor and the inner wall of thetubing. Operatively attached to the lower end of motor 16 is a pressuremultiplying pump 17. This pressure multiplying pump operates on theprinciple of employing a small fluid pressure against a piston of largediameter with the total force on the large diameter piston beingtransferred to a small diameter piston which then providcs a muchgreater pressure. Such pressure increasing pumps are well known and arecommercially available from equipment supply houses. A fluid motor-pumpcombination which is suitable for use as motor 16 and pump 17 in theapparatus of FIGURE 2 is illustrated and described on page 2896,Composite Catalog of Oil Field Equipment and Services, 1957, publishedby World Oil, Houston, Texas. The drilling mud is exhausted from thelower side of the fluid motor 16 through an annulus 38. A small portionof the mud enters the pump 17 and is exhausted therefrom through apressure pipe 20 under high pressure. The remainder of the mud flows ondownward around pump 17. This mud from pipe 20, under an extremely highpressure, passes on through conduits 22 to the nozzles 23 for impingingat high velocity around the periphery of the borehole. Reference numeral24 identifies the high pressure fluid jets from nozzles 23. The drillingmud which emerges from nozzles 23, then entrains cuttings and flowsupward through annulus 39 between the drill tubing 12 and the walls ofthe borehole. The drilling mud not entering the pump 17 bypasses thepump and flows on downward and through one or more conventional jets 34.This added volume of drilling mud, along with the mud emerging from thetwo high pressure nozzles, carries all of the cuttings, that is, thoseproduced by the high pressure liquid jets and the cuttings produced bythe drill cones, upward through annulus 39. The mud with the entrainedcuttings leaves the annulus 39 and flows through a pipe into a separator31 which removes the cuttings from the drilling mud. Separator 31 can,if desired, be suitable centrifuge. Mud free or substantially free fromcuttings flows from the centrifuge into tank 29 from which mud pump 28takes suction for recirculation of the mud. Reference numeral 37identifies a swivel such as is used for connecting a rotating conduit toone which does not rotate. Pressure pipe 20 is attached by threads 21,or other suitable means, to the body of drill bit 13.

Engine 32 is illustrated as being the prime mover for rotation of adrive shaft 33a which is provided with a pinion gear, not shown. Thisgear meshes with a rack, also not shown, integral with the drivehead 33for rotation of the drill tubing and drill bit.

In FIGURE 3 the position of the drill cones with re spect to one anotheris illustrated. There is also illustrated in this figure positioning ofthe conventional jets 34 through which the major portion of the drillingmud passes.

In FIGURE 4 is illustrated an embodiment of this invention in which thecutting fiuid is a gas, such as air. In this embodiment a compressor 59compresses air to an extremely high pressure and the air passes througha conduit 60a, a swivel 60, into drill tubing 52. High pressure air orgas in this tubing is identified by reference numeral 57. This highpressure gas passes down the tubing into the body of drill bit 53 andthrough nozzles 55 which are positioned or oriented in the same manneras described above relative to FIGURE 2. These nozzles are supported bynozzle bases 54. Drill cones 56 are provided for drilling or crushingthe core remaining in the center of the well bore. The gas emerging fromnozzles 55 entrains the cuttings produced by the air emerging from thenozzles and the cuttings produced by the drill cone, and carries thecuttings up annlus 58 for exhaust through pipe 65. Reference numeral 51identifies the well bore while reference numerals 61 and 62 identify,respectively, the drivehead and the engine. The groove cut by the highpressure gas in the bottom of the well is identified by referencenumeral 63.

The gas pressure suitable for such a drilling operation is of the orderfrom 5,000 to 50,000 (pounds per square inch gage) at the inlet to thenozzles.

The embodiment of drill bit illustrated in FIGURE 5 is provided withseveral nozzle inserts 73 which are provided with nozzle openings 72 forcovering the entire diameter of the borehole. This drill bit 71 is notprovided with drill cones because the several jets of gas are intendedto do the entire drilling job. Pressures of gas for drilling with thebit 71 are the same as mentioned above for use in the embodiment ofapparatus illustrated in FIG- URE 4.

In FIGURE 6 is illustrated an embodiment of this invention in whichsolid pellets are entrained in the high pressure drilling mud toincrease the drilling rate over that possible when using drilling mudalone. In this embodiment the drilling is carried out in a well bore 81under a mud pressure of 5,000 to 20,000 pounds per square inch gage ormore at the inlet of the nozzles. The high pressure mud pump 93discharges the mud into a conduit 30 for passage to drill tubing 82. Aportion of the mud from conduit is by passed therefrom through a conduit79 which communicates with means 99 for adding pellets into the highpressure mud stream. The operation of this means 99 is relatively simpleand merely involves operating the valves to provide communication frompipe 79 through tank 77 or through tank 78 to pipe 30 again. Forexample, with tank 78 previously filled with pellets to be added to thehigh pressure drilling mud, the valves are regulated for providingcommunication from pipe 79 by way of tank 77 to conduit 80, with thevalves for use with tank 78 being closed. Upon admission of drilling mudfrom pipe 79 to tank 77, pressure is equalized therein and pellets thenflow by gravity into conduit 80 at any desired rate. While pellets arebeing transferred from tank 77 to conduit 80, the valves above tank 78are opened and the tank is filled with pellets from a hopper 74 disposedthereabove. Drilling mud containing pellets in suspension within drilltubing 82 is identified by reference numeral 86 and this pellet-ladenmud flows on downward and through nozzles 35 for cutting annular groove89. Engine 92 by way of drivehead 91 rotates the tubing and drill bit83. Upon rotation of this drill bit, the pelletladen mud cuts the groove89 while the drill cone or cones S8 drill or crush the core from thecenter of the borehole. The cuttings produced in the drilling operationand the pellets are carried upward by the mud in annulus 87. The mud,cuttings and pellets pass from the top of the annulus through conduit 98to a pellet and cutting separator 97 from which the cuttings emergethrough a conduit 76 for such disposal as desired and the pellets passinto pellet receiver 96. From this pellet receiver 96 the pellets aretransfer-red by means not shown to a belt 75 for addition into hopper74. A magnet 100 is provided for removing any iron separated with thepellets. The drilling mud, free or substantially free from cuttings andfree from pellets, is discharged from the separator 97 into a mud tankfrom which the pump 93 takes suction.

Pellets suitable for use in the embodiment of this invention can besmall iron or steel balls or sand grains such as Ottawa sand. When ironor steel pellets are used, the magnet 100 is obviously not used.

When using iron or steel pellets, it is preferable to employ pellets ofabout ;-inch to 41-inch in diameter. From about one to 200 pounds ofsteel pellets per barrel of drilling mud can be used. When using pelletssuch as Ottawa sand, with grains of the sand being well rounded and fromabout -inch to /S-iIlCh in diameter, about one to 100 pounds of sand perbarrel of mud is used.

According to this invention it is preferable to use rounded pelletsrather than sharp angular materials because sharp angular materials tendto abrade the conduits through which they pass and particularly tonozzles through which they are ejected at high velocity. The materialsfor making the nozzles for use according to this invention are selectedfrom among those commercially available, taking into considerationresistance desired to abrasion by gas and by drilling mud containingsuspended suspended solid pellets.

The principles of this invention are adaptable for drilling wells inwhich core samples are taken as well as drilling wells in which the coreis drilled out by conventional drill cones as described hereinabove. Adrill bit suitable for high pressure fluid drilling and taking a core isillustrated in FIGURE 7. \Vithin the bit illustrated in FIG- URE 7, acore barrel is used for recovery of a core. The use of core barrels iscommon and a core barrel is not illustrated in the drawing nor describedherein. The need and the use of such equipment is well understood bythose skilled in the art. The length of this drill bit will becontrolled by the length of the core it is desired to take. The bit iscomposed of an outer cup-shaped shell Still within which is inserted aninner or second cupshaped shell 162. These two shells are positionedconcentrically and are so spaced from one another as to provide anannular space 107 between them. This annular space is sealed at itsbottom by an annular plate 1%. The plate W9 is provided with one or moreopenings into which nozzles Hi3, containing nozzle openings 106, areinserted. Threads or other means Hi5 are provided for attaching thisdrill bit to the bottom end of a drill tubing, not shown. Conduit 168 isfor passage of high pressure drilling mud or high pressure gas forinjection through the nozzle openings 1%. The fluid containing drillcuttings in suspension passes upward between the outer surface of theouter shell 191 and the walls of the borehole for passage up the annulusof the well. Obviously some high pressure fluid with cuttings insuspension passes upward between the inner wall of the inner shell 102and the outer wall of a core, and conduits 104 are provided through thisdouble shell drilling bit so that this latter mentioned fluid, withcuttings in suspension, can be ejected from the well. FIGURE 8illustrates the appearance of the bottom of the drilling bit of FIGURE 7The nozzles 1% in this particular case are oval or elliptical in crosssection with the long axis being normal to the radius of the drill bit.The long axis of these nozzles being positioned in this manner increasesthe rate of drilling because the high pressure fluid is ejected againsta particular point for a longer period of time during the rotation ofthe bit than if the nozzles were oriented in any other direction or wereround in section. However, the nozzles can be round in cross section, ifdesired. The nozzles as illustrated in FIGURE 7 are so oriented thattheir longitudinal axis slopes in the direction of rotation, asillustrated by nozzle 106a. It is also preferable, in some instances, toslope two nozzles slightly toward the outer periphery and the other twonozzles, when four nozzles are used, toward the inner periphery of thedrill bit of FIGURE 7. The nozzles in this case are so oriented in orderto cut a groove sufficiently wide that the annular drill can advancedownward therein.

In FIGURE 9 is illustrated a drill bit quite similar to that of FIGURE 8but this drill bit is provided with one or more drill cones 12th in sucha manner that the core is drilled up and accordingly is not saved forinspection. In this embodiment the drill is composed of an outercup-shaped shell 111 with an inner cup-shaped shell 12 .2 so disposed asto provide an annular space 117 therebetween. An annular plate 119 sealsthis annulus at its bottom. Nozzle inserts 113, provided with ellipticalor oval cross section nozzle openings are inserted through plate H9.Conduit or conduits 114 are provided for passage of drilling fluid withcuttings in suspension from within the inner shell 112 to the annulusbetween the drill tubing and the borehole wall. Threads 115 are providedfor attaching this drill bit to the lower end of a drill tubing andconduit 118 is for passage of high pressure fluid from the drill tubing,not shown, into the drill bit. FIG- URE is a bottom end view of thedrill bit of FIGURE 9. FIGURE 10 illustrates the positioning of thedrill 6 cones lit) with respect to the inner wall of the inner shell112. As shown in FIGURES 9 and 10, the bottom of the annular plate 119is provided with teeth 121 more or less similar to the teeth provided inwashover drill bits.

The pelletized fluid can be used with the drill bits illustrated in allof the figures excepting FIGURE 4, which uses a high pressure gas as thecutting fluid.

The high pressure mud driven motor 16 and pump 17 of FIGURE 2 can beeither rotary or reciprocating equipment whichever is deemed mostsuitable for the problem at hand.

Such a drilling mud as one containing a bentonitic clay is suitable foruse according to this invention. Such a drilling mud with sand or otherpellets in suspension is used at pressures of 2500 psi. and above or ashigh as 20,000 p.s.i., at the inlets to the nozzles, for drillingaccording to this invention.

Since the hereinbefore-mentioned high pressures are present only withinthe drill tubing and drill bit and upstream of the jetting orifices,those pressures are not present at any location in the well bore bywhich drilling apparatus could be ejected. Furthermore, the combinedweights of drill bits, drill collars and drill tubings are many tons andsuch apparatus is just not blown from the wells by high pressure fluidwithin the drill tubing and collars.

While certain embodiments of the invention have been described forillustrative purposes, the invention obviously is not limited thereto.

I claim:

1. A method for drilling a well comprising impinging a stream of fluidat a pressure greater than conventional well fluid circulating pressureand at high velocity downwardly and directly against an earth formationat the bottom of said well and adjacent the wall of said well, movingthe downwardly impinging stream of fluid around the wall of said wellthereby cutting an annular groove around the periphery and below thebottom of said well and producing cuttings and leaving a centrallylocated core of said formation, crushing said core, passing additionalfluid at bottom hole, circulating pressure into the crushed core andsaid cuttings, suspending the crushed core and said cuttings in thecombined impinged fluid and said additional fluid, and exhausting thecombined impinged fluid and additional fluid carrying the crushed coreand cuttings in suspension from said well.

2. The method of claim 1 wherein said fluid is a gas.

3. The method of claim 1 wherein said fiuid is a liquid.

4. The method of claim 1 wherein said fluid is a drilling mud.

5. The method of claim 1 wherein said fluid is a drilling mud containingsolid, diflicultly breakable pellets.

6. A method for drilling a well comprising pumping a stream of wellfluid downwardly in a drill tubing in said well at conventional wellfluid circulating pressure, dividing the well fluid into two portions,pumping one portion to a pressure hi her than said circulating pressure,impinging this fluid of higher pressure at a high velocity downwardlyand directly against an earth formation at the bottom of said well andadjacent the wall thereof, moving the downwardly impinging stream offluid around the wall of said well thereby cutting an annular groovearound the periphery and below the bottom of said well and producingcuttings and leaving a centrally located core of said formation,crushing said core, passing the remaining portion of fluid at bottomhole circulating pressure into the crushed core and said cuttingsthereby suspending said cuttings and said crushed core in the combinedportions of said fluid, and exhausting the combined portions of fluidcarrying the cuttings and crushed core in suspension from the well.

7. The method of claim 6 wherein said well fluid is a drilling mud.

8. The method of claim 6 wherein said Well fluid is a drilling mudcontaining solid, difilculty breakable pellets.

References Cited in the file of this patent UNITED STATES PATENTS 8Brantly May 23, 1939 Ledgerwood Jan. 4, 1955 Deily Nov. 22, 1955 ShieldsMar. 13, 1956 Goodwin Sept. 3, 1957 Ramsey et a1. July 1, 1958 MacNeilSept. 30, 195 8 Scott Aug. 25, 1959

1. A METHOD FOR DRILLING A WELL COMPRISING IMPINGING A STREAM OF FLUID AT A PRESSURE GREATER THAN CONVENTIONAL WELL FLUID CIRCULATING PRESSURE AND AT HIGH VELOCITY DOWNWARDLY AND DIRECTLY AGAINST AN EARTH FORMATION AT THE BOTTOM OF SAID WELL AND ADJACENT THE WALL OF SAID WELL, MOVING THE DOWNWARDLY IMPINGING STREAM OF FLUID AROUND THE WALL OF SAID WELL THEREBY CUTTING AN ANNULAR GROOVE AROUND THE PERIPHERY AND BELOW THE BOTTOM OF SAID WELL AND PRODUCING CUTTINGS AND LEAVING A CENTRALLY LOCATED CORE OF SAID FORMATION, CRUSHING SAID CORE, PASSING ADDITIONAL FLUID AT BOTTOM HOLE, CIRCULATING PRESSURE INTO THE CRUSHED CORE AND SAID CUTTINGS, SUSPENDING THE CRUSHED CORE AND SAID CUTTINGS IN THE COMBINED IMPINGED FLUID AND SAID ADDITIONAL FLUID, AND EXHAUSTING THE COMBINED IMPINGED FLUID AND ADDITIONAL FLUID CARRYING THE CRUSHED CORE AND CUTTINGS IN SUSPENSION FROM SAID WELL. 